## Presentation on theme: "Electromagnetic Radiation"— Presentation transcript:

transverse waves produced by the motion of electrically charged particles does not require a medium speed in a vacuum = 300,000 km/s electric and magnetic components are perpendicular E=mc2

absorbed and released by electrons energy increases with wave frequency

B. EM Spectrum long  low f low energy short  high f high energy

AM - amplitude modulation Microwaves penetrate food and vibrate water & fat molecules to produce thermal energy

slightly lower energy than visible light can raise the thermal energy of objects thermogram - image made by detecting IR radiation

C. Types of EM Radiation Visible Light
small part of the spectrum we can see ROY G. BIV - colors in order of increasing energy R O Y G. B I V red orange yellow green blue indigo violet

slightly higher energy than visible light Types: UVA - tanning, wrinkles UVB - sunburn, cancer UVC - most harmful, sterilization

Ozone layer depletion = UV exposure!

C. Types of EM Radiation X rays higher energy than UV
can penetrate soft tissue, but not bones Used to be used to size shoes before harmful affects were known.

CHECK UNDERSTANDING 1. A light wave is an electromagnetic wave that has both an electric and magnetic component associated with it. Electromagnetic waves are often distinguished from mechanical waves. The distinction is based on the fact that electromagnetic waves ______. a. can travel through materials and mechanical waves cannot b. come in a range of frequencies and mechanical waves exist with only certain frequencies c. can travel through a region void of matter and mechanical waves cannot d. electromagnetic waves cannot transport energy and mechanical waves can transport energy e. electromagnetic waves have an infinite speed and mechanical waves have a finite speed

All waves have the same speed which depends on the medium
Check Understanding a. Which region of the electromagnetic spectrum has the highest frequency? b. Which region of the electromagnetic spectrum has the longest wavelength? c. Which region of the electromagnetic spectrum will travel with the fastest speed? GAMMA RAY RADIO WAVE All waves have the same speed which depends on the medium

Check Understanding a. Which color of the visible light spectrum has the greatest frequency? b. Which color of the visible light spectrum has the greatest wavelength? VIOLET RED

Light II. Light and Color Light and Matter Seeing Colors Mixing Colors

A. Light and Matter Opaque absorbs or reflects all light Transparent
allows light to pass through completely Translucent allows some light to pass through

B. Seeing Colors White light contains all visible colors - ROY G. BIV
In white light, an object… reflects the color you see absorbs all other colors REFLECTS ALL COLORS ABSORBS ALL COLORS

Video: How Cones and Rods Work Stimulates red & green cones
B. Seeing Colors Video: How Cones and Rods Work Stimulates red & green cones The retina contains… Rods - dim light, black & white Cones - color red - absorb red & yellow green - absorb yellow & green blue - absorb blue & violet Stimulates all cones

Test for red-green color blindness.
B. Seeing Colors Test for red-green color blindness. Color Blindness one or more sets of cones does not function properly

View Java Applet on primary light colors.
C. Mixing Colors Primary light colors red, green, blue additive colors combine to form white light EX: computer RGBs View Java Applet on primary light colors.

View Java Applet on filters.
C. Mixing Colors Filter transparent material that absorbs all light colors except the filter color View Java Applet on filters.

C. Mixing Colors Pigment
colored material that absorbs and reflects different colors Primary pigment colors cyan, magenta, yellow subtractive colors combine to form black EX: color ink cartridges

C. Mixing Colors Light Pigment
When mixing pigments, the color of the mixture is the color of light that both pigments reflect.

Bill Nye Explains Color